IXIARO® JESPECT® Japanese Encephalitis Vaccine Clinical Trials, Dosage, Indication, Side Effects
Valneva SE's IXIARO® (JESPECT® in Australia and New Zealand) is an inactivated, adsorbed Vero cell culture-derived vaccine targeting the Japanese encephalitis virus (JEV). It is prepared by propagating the JEV strain SA14-14-2 in Vero cells. Multiple viral harvests are pooled, clarified, and concentrated. The virus suspension is treated with protamine sulfate to remove contaminating DNA and proteins. The partially purified virus is processed and fractionated through sucrose density gradient centrifugation. Each fraction is analyzed for the presence of the virus, and fractions with the highest virus activity are pooled to give a purified virus suspension. The purified virus is then inactivated by formaldehyde treatment. IXIARO's final preparation is adjusted to a specified protein concentration and formulated by adding aluminum hydroxide.
The IXIARO JEV was developed through a cooperative research and development agreement with the Walter Reed Army Institute of Research. In 2018, the U.S. Food and Drug Administration (FDA) issued STN: BL 125280, which included a statistical review, Clinical Review, and toxicology review. An approval letter was issued on October 4, 2018.
The U.S. Department of Defense (DoD) has relied on IXIARO since 2010 to help protect personnel deployed to JE-endemic areas for whom JE vaccination is recommended. Under a new one-year contract announced on September 25, 2023, the DoD will purchase a minimum of $32 million in IXIARO® vaccines and may buy additional doses over the next 12 months. Vaccine deliveries will commence in 2023. On January 30, 2025, Valneva announced a new one-year contract under which the DoD will purchase a minimum of $32.8 million worth of IXIARO and may purchase additional doses over the following 12 months.
A study estimated that between 2000 and 2015, 307,774 JE cases (95% CI: 167,442–509,583) were averted globally due to vaccination. The UK Health Security Agency published new guidance on JE vaccination in the 'Green Book' (Chapter 20) in February 2024. On September 5, 2024, the U.S. CDC published the Japanese Encephalitis Vaccine Evidence to Recommendations Framework and updated the JE Yellow Book 2026 in April 2025.
France-based Valneva SE (Nasdaq: VALN; Euronext Paris: VLA) is a specialty vaccine company focused on developing vaccines for diseases with significant unmet needs. For more information, visit www.valneva.com. Valneva USA, Inc. is located at 910 Clopper Road, Suite 160S, Gaithersburg, MD 20878, USA.
IXIARO Vaccine Availability 2025
As of 2025, IXIARO is the only Japanese encephalitis vaccine approved by the U.S. FDA, which is commercially available at various travel vaccine retailers. IXIARO/JESPECT is licensed for adults in the United States, Australia, New Zealand, Europe, Canada, Germany, Switzerland, Hong Kong, Singapore, Israel, Norway, Liechtenstein, Iceland, Japan, the United Kingdom, and the Republic of Korea. In all other licensed territories, IXIARO®/JESPECT® is indicated for use by adults. In Germany, CSL Seqirus will distribute IXIARO®.
Visit PreventJE.com, a website for travel health professionals and their patients focusing on the risk and prevention of Japanese encephalitis in travelers to Asia. In Australia, information on eligibility for the free JE vaccine is available on the NSW Health website.
IXIARO Vaccine Approvals
In March 2009, the U.S. Food and Drug Administration (FDA) approved JE-VC for adults aged 17 years and older. In June 2009, the CDC's Advisory Committee on Immunization Practices (ACIP) approved recommendations for the use of JE-VC in adults. In September 2010, the FDA approved a JE-VC booster dose for adults. In May 2013, FDA approval for JE-VC was extended to include children aged two months through 16 years. ACIP recommendations for the pediatric use of JE-VC were approved in June 2013. In April 2018, the FDA approved a booster dose for the pediatric age group. On March 8, 2020, Valneva announced that the FDA approved an extension of the shelf life of IXIARO from 24 months to 36 months.
IXIARO Indication
IXIARO is indicated for active immunization to prevent disease caused by the JEV, the leading cause of vaccine-preventable encephalitis, and is approved by the U.S. CDC for use in individuals two months of age and older. The CDC says travelers to areas at risk for Japanese encephalitis should discuss the need for vaccination with their healthcare provider. JE is a deadly infectious disease occurring throughout most of Asia and parts of the western Pacific, spread by mosquitoes, pigs, and sheep. JE is fatal in approximately 30% of those who show symptoms, leaving half of the survivors with permanent brain damage.
IXIARO Side Effects
IXIARO contains protamine sulfate, a compound known to cause hypersensitivity reactions in some individuals. Therefore, severe allergic reaction (e.g., anaphylaxis) after a previous dose of IXIARO®, any other Japanese encephalitis vaccine, or any component of IXIARO®, including protamine sulfate ─ a compound known to cause hypersensitivity reactions in some individuals ─ is a contraindication to the administration of IXIARO®. Individuals with a history of severe allergic reaction to another Japanese encephalitis vaccine may be referred to an allergist for evaluation if immunization with IXIARO is considered. The most common ( > 10%) adverse reactions were fever, irritability, diarrhea, and injection site redness in infants two months to < 1 year of age; fever in children 1 to < 12 years of age; pain and tenderness in adolescents 12 to < 18 years of age; and, headache, myalgia, and injection site pain and tenderness in adults.
IXIARO Dosage
IXIARO is administered by intramuscular injection and is approved for use in individuals 2 months of age and older. In 2019, the U.S. CDC's ACIP committee strengthened its language on booster doses, stating they should be given at least 1 year after the primary series if the person is experiencing ongoing or re-exposure to the JE virus.
Primary Series: Children 2 months to <3 Years of age: Primary immunization with IXIARO consists of two (2) 0.25 mL doses, administered 28 days apart; Individuals 3 years of age and older: Primary immunization with IXIARO consists of two (2) 0.5 mL doses, administered 28 days apart; Complete the primary immunization series at least one week before potential exposure to JEV.
Booster Dose: Individuals 17 years of age and older: If the primary series of two doses was completed more than one year previously, a booster dose might be given if ongoing exposure or re-exposure to JEV is expected; Infants, children, and adolescents two months to <17 years of age: The safety and immunogenicity of a booster dose have not been evaluated.
Immunocompromised individuals may have a diminished immune response to IXIARO.
U.S. CDC Japanese Encephalitis Vaccine Recommendations
The U.S. CDC developed Japanese Encephalitis vaccine recommendations using an explicit evidence-based method based on the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach.
Japanese Encephalitis Outbreaks
The World Health Organization (WHO) states that JE outbreaks intensify during the rainy (monsoon) season in Asia (India, Nepal) and the Pacific (Australia), when vector populations increase.
IXIARO Vaccine Sales
In the first half of 2025, IXIARO® /JESPECT® sales increased by 30.6% to €54.7 million compared to €41.9 million in the first half of 2024. Sales to both travelers and the DoD grew in double digits compared to the first half of 2024, when IXIARO® supply constraints impacted sales.
In 2024, IXIARO/JESPECT sales increased by 28% to €94.1 million, demonstrating double-digit growth among travelers and the U.S. Department of Defense compared to 2023. Valneva has been supplying additional doses of IXIARO® to the U.S. DoD under the current contract, signed in September 2023.
IXIARO Vaccine News
August 12, 2025 - Peter Bühler, Valneva's Chief Financial Officer, commented, "We also substantially reduced our spending and successfully leveraged our ATM program to welcome two new leading healthcare investors among our main shareholders, strengthening our financial position ahead of this important clinical catalyst."
January 30, 2025 - Dipal Patel, Chief Commercial Officer of Valneva, commented, "We are honored to continue our long-term relationship with the DoD. The U.S. military has trusted IXIARO® for over ten years to help protect military personnel, their families, civilian government service personnel, and government contractors from this potentially deadly disease."
November 7, 2024 - Valneva anticipates receiving new vaccine orders in 2025.
October 31, 2024 - Victoria's Minister for Health, Mary-Anne Thomas, stated, "Following expert advice from the Chief Health Officer, we're expanding this important program to ensure more Victorians can access the free JEV vaccine and protect themselves and their loved ones this summer."
May 15, 2024 - The U.S. CDC published Japanese Encephalitis Vaccine Information for Healthcare Providers.
September 25, 2023 - Dipal Patel, Chief Commercial Officer of Valneva SE, commented, "We are excited to continue our long-term relationship with the DoD. The U.S. military has trusted IXIARO® for over ten years to help protect military personnel, their families, civilian government service personnel, and government contractors from this potentially deadly disease."
September 21, 2023 - Valneva SE confirmed it distributes IXIARO® directly to the U.S. DoD.
July 11, 2022 - A non-peer-reviewed study: Safety and immunogenicity following co-administration of Yellow fever vaccine with Tickborne encephalitis or Japanese encephalitis vaccines concluded: Inactivated TBEV or JEV vaccines can be co-administered with the live attenuated YFV vaccine without an increased risk of adverse events and reduced development of nAbs to the respective viruses.
September 3, 2021 - Valneva SE announced that the U.S. Department of Defense had exercised the first option of the contract signed in September 2020 to purchase a further supply of its Japanese encephalitis vaccine, IXIARO®.
July 19, 2019 - The CDC's Advisory Committee on Immunization Practices (ACIP) Recommendations for Japanese Encephalitis Vaccine were updated.
June 5, 2019: The European Medicines Agency approved the extension of the shelf life of the Japanese encephalitis vaccine IXIARO from 24 months to 36 months.
March 1, 2019 – At its meeting on February 27, 2019, the U.S. CDC's ACIP voted unanimously to expand the JEV vaccination recommendations.
Ixiaro Clinical Trials
Ixiaro Japanese Encephalitis vaccine has been involved in over 60 clinical trials.
